The present invention relates to a friction stir welding apparatus and a method of operating a friction stir welding apparatus. The Friction stir welding apparatus is usually attached to a distal end of an arm of an articulated robot.
In recent years, friction stir welding has been widely used as a joint technology without causing a deformation of workpieces to be joined together due to heat generating in the welding process. Friction stir welding is a joining process for joining two members (workpieces) together along a joint line at a joint region (butted region) of the two workpieces by rotating and pressing a rotary tool against the joint region and gradually inserting the same into the joint line, so that the material of the workpieces undergoes plastic deformation under the rotating force of the rotary tool, allowing the rotary tool to move along the joint line to thereby join the two workpieces together.
A friction stir welding apparatus is known, for example, by Japanese Laid-open Patent Application No. 2002-103061. This friction stir welding apparatus includes a retaining arm, to which a rotary tool and a receiving table are fixed in a position opposite to each other. The retaining arm of the friction stir welding apparatus is attached to a distal end of an arm of an articulated robot (hereinafter referred to as a robot arm) so that the friction stir welding apparatus is movable in three-dimensional directions through the robot arm. Meanwhile, workpieces are set on a work table, whose lower surface is provided with feed rollers. The friction stir welding apparatus is operated such that after the upper surface of the receiving table is adjusted to come into contact with the rollers so that the reaction force is applied to the friction stir welding apparatus, the rotary tool which is rotating is pressed against and inserted into the workpieces and then moved along the joint line of the workpieces, to thereby join the two workpieces together.
According to this friction stir welding apparatus, since the receiving table is fed by the feed rollers of the work table, the receiving table is capable of moving only in the feeding direction of the feed rollers during the welding process of the workpieces. Therefore, if the workpieces are joined together along a joint line extending in two or more directions, it is necessary to change the direction of the workpieces and set them on the work table whenever the direction of the joint line changes. This requires much time and labor, and thus increases the production cost in the end.
With the foregoing drawback of the prior art apparatus in view, the present invention seeks to provide a friction stir welding apparatus and a method of operating a friction stir welding apparatus, which can be readily used with workpieces to be welded along a joint line extending in two or more directions.